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BADSECT(8)		  BSD System Manager's Manual		    BADSECT(8)

     badsect --	create files to	contain	bad sectors

     badsect bbdir sector ...

     The badsect utility makes a file to contain a bad sector.	Normally, bad
     sectors are made inaccessible by the standard formatter, which provides a
     forwarding	table for bad sectors to the driver.  If a driver supports the
     bad blocking standard it is much preferable to use	that method to isolate
     bad blocks, since the bad block forwarding	makes the pack appear perfect,
     and such packs can	then be	copied with dd(1).  The	technique used by this
     program is	also less general than bad block forwarding, as	badsect	cannot
     make amends for bad blocks	in the i-list of file systems or in swap ar-

     On	some disks, adding a sector which is suddenly bad to the bad sector
     table currently requires the running of the standard DEC formatter.  Thus
     to	deal with a newly bad block or on disks	where the drivers do not sup-
     port the bad-blocking standard badsect may	be used	to good	effect.

     The badsect utility is used on a quiet file system	in the following way:
     First mount the file system, and change to	its root directory.  Make a
     directory BAD there.  Run badsect giving as argument the BAD directory
     followed by all the bad sectors you wish to add.  (The sector numbers
     must be relative to the beginning of the file system, but this is not
     hard as the system	reports	relative sector	numbers	in its console error
     messages.)	 Then change back to the root directory, unmount the file sys-
     tem and run fsck(8) on the	file system.  The bad sectors should show up
     in	two files or in	the bad	sector files and the free list.	 Have fsck(8)
     remove files containing the offending bad sectors,	but do not have	it re-
     move the BAD/nnnnn	files.	This will leave	the bad	sectors	in only	the
     BAD files.

     The badsect utility works by giving the specified sector numbers in a
     mknod(2) system call, creating an illegal file whose first	block address
     is	the block containing bad sector	and whose name is the bad sector num-
     ber.  When	it is discovered by fsck(8) it will ask	"HOLD BAD BLOCK	?".  A
     positive response will cause fsck(8) to convert the inode to a regular
     file containing the bad block.

     The badsect utility refuses to attach a block that	resides	in a critical
     area or is	out of range of	the file system.  A warning is issued if the
     block is already in use.


     The badsect utility appeared in 4.1BSD.

     If	more than one sector which comprise a file system fragment are bad,
     you should	specify	only one of them to badsect, as	the blocks in the bad
     sector files actually cover all the sectors in a file system fragment.

BSD				 June 5, 1993				   BSD


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